Cleaning apparatus protection mechanism



Aug. 16, 1966 R. L. BROWN ET AL 3,266,078

CLEANING APPARATUS PROTECTION MECHANISM Filed April 3, 1964 ll "I F I 9- 4 INVENTORS En YMUIVD L Brown BY Jam/J. Kowolswsm THEYR ATTORNEY United States Patent 3,266,078 CLEANING APPARATUS PRDTECTHON MECHANISM Raymond L. Brown, Banksville, N.Y., and John J. Kowalewski, Riverside, Conn, assignors to Electrolux Corporation, Old Greenwich, Conn, a corporation of Delaware Filed Apr. 3, 1964, Ser. No. 357,174 6 Claims. (Cl. 15-319) This invention pertains to the prevention of belt breakage and motor burnout in, among other things, vacuum cleaning apparatus wherein a surface-cleaning suction nozzle has included therein a surface-agitating rotary brush rotated by a motor-driven belt.

The above described cleaning nozzle greatly improves surface cleaning, particularly of certain types of synthetic materials, by using the beneficial effects of suction and brush agitation simultaneously. For example, when cleaning a carpet the rotating brush agitates the carpet, fi-uflFs its nap, and dislodges dust, dirt, lint and litter from the carpet so that the applied suction can carry the dislodged matter away from the suction nozzle to a suitable collector, such as a dust bag remotely situated in a tank or canister unit.

In such a nozzle it is desirable to employ a toothed belt which is meshed wit-h the teeth of a motor-driven pinion gear, or driving gear, and a brush-rotating pinion gear, or driven gear. With such an arrangement a positive non-slipping driving action is obtained. More torque is transmitted from the driving pinion to the driven pinion and rotary brush. Also, with such a positive drive arrangement the rotary brush will not become stalled or jammed very easily.

However, on occasion the rotary brush does become stalled; for example, when metallic objects such as hair clips, nails or coins become lodged between the brush and a wall portion of the suction nozzle. Also, the rotary brush will stall when a suflicient amount of a rug fringe or the stringy ends of a frayed carpet become wound about the brush. .When the brush does stall the section of the now stationary belt, which normally meshes with the rotating motor-driven pinion gear, is moved outward from the driven pinion gear due to the high torque applied to the belt by the driven pinion gear thereby removing most of the belt teeth from meshing engagement with the rotating pinion gears teeth, leaving one, or a few, of the belt teeth meshed with the teeth on the rotating pinion gear. But, these teeth are only partially meshed. Consequently, the motor, being then lightly loaded, runs at a much higher speed, as does the rotating driven pinion gear coupled therewith. Since the driven pinion gears partially meshed teeth are now moving at greater speed they slip completely out of engagement with the one or few belt teeth with which they were successively partially engaged and the fast moving pinion gear teeth successively impact against and abrade the same one, or few, belt teeth. Eventually, these belt teeth and the fibre reinforcing therein will become worn and the belt will break. Since the stalling torque of brush is not transmitted through the belt to overload the motor a circuit breaker, connected with the motor, will not function to disconnect the motor and prevent breakage of the belt.

Therefore, the main object of the present invention is to prevent belt breakage and motor burnout in apparatus employing motor driven belt transmissions such as, for example, in the vacuum cleaner apparatus hereinbefore described.

In order to realize the aforementioned objective that section of the belt which is in meshing engagement with the motor-driven pinion gear is forced to remain fully 3,266,678 Patented August 16, 1966 meshed therewith even when the brush-rotating pinion gear and rotary brush are stalled; i.e., the teeth in that portion of the :belt which is in meshing engagement with the teeth of the motor-driven pinion gear are prevented from moving outwardly therefrom, out of mesh with the teeth of the motor-driven pinion gear. As a consequence of preventing such disengagement, the 'belt, when it is subjected to the overload experienced by the rotary brush, overloads the motor-driven pinion gear and its driving motor so that the circuit breaker can operate to electrically disconnect the motor thereby preventing belt breakage and motor burnout.

Further objects and advantages of our invention will be apparent from the following description when considered in conjunction with the accompanying drawings in which:

FIG. 1 is a plan view, cut away for purposes of clarity, of a surface cleaning suction nozzle incorporating the subject invention;

FIG. 2 shows a side section of the surface cleaning suction nozzle of FIG. 1, as viewed along the section line 2-2 of FIG. 1;

FIG. 3 is a fragmentary view, somewhat enlarged, showing a portion of the section shown in FIG. 2;

FIG. 4 is another side section of the surface cleaning suction nozzle of FIG. 1, as viewed along the section line 4-4 of FIG. 1;

FIG. 5 is a side section on :a reduced scale of the surface cleaning suction nozzle of FIG. 1, as viewed along the section line 5-5 of FIG. 1; and,

FIG. 6 is a somewhat diagrammatic illustration of a prior art belt drive arrangement showing the activity of the various elements of the belt drive arrangement as the suction nozzles rotary brush stalls.

In FIGS. 15 the reference number 10 designates a surface cleaning suction nozzle in which the subject invention is incorporated. The nozzle 10 includes a motor 12, a circuit breaker 14 for protecting the motor and a surface agitating lbrush 16 which is rotated by the motor through a belt drive arrangement hereinafter described. A hollow wand 18 is coupled with the nozzle 10 as shown. A small diameter conduit 20 integral with, but separate from, a large diameter central duct 22 of the wand 18 has an insulated two-wire cord 24 passing therethrough. The cord 24 supplies electrical energy to the motor 12 through its protective circuit breaker 14.

When the nozzle 10 is to be readied for use the wand 18 is coupled to a tank unit (not shown) of a vacuum cleaner through a suction hose (not shown) and the electric cord 24 is connected with another cord (not shown) which is carried along the suction hose and then into the vacuum cleaners tank unit to a pair of electrically energized terminals. operationally, rotation of the brush 16 dislodges dirt and dust from the surface being cleaned and this dislodge-d matter is drawn by suction through the nozzle 10, the wands duct 22 and the suction hose into a dust bag remotely located in the vacuum cleaner tank unit.

As indicated the nozzle 10 includes a base member 26, a top cover 28 and a bottom cover plate 3%. The base member 26, which may be an aluminum alloy casting, has internally threaded bosses 32 formed on top thereof. These bosses 32 serve as mounts for the motor- 12. The end bells 34 and 36 of the motor 12 have apertures so that screws 38 can pass therethrough and thread ably engage the internal threads in the bosses 32. Rubber washers 40, which serve as vibration dampers, are located between the screw receiving parts of the end bells and the heads of the screws 38, as well as between the screw receiving parts of the end bells and the top of the bosses 32. The base member 26 has formed therein a semicylindrical wall portion 42 (FIG. 5) which defines a semi-cylindrical trough or space 44 (FIG. 1) on the underside of the base member 26. The rotary brush 16 which is comprised of a spindle 46 having an array of bristles 48 extending therefrom is journaled for rotation in the side walls of the base members wall portion 42 and the brush 16 is received in the trough or space 44. As shown in FIG. 5 the bottom cover plate 39 has a longitudinal slot 50 therein through which dust, and dirt from a surface to be cleaned (e.g., a carpet or rug) enters the nozzle 10. After entry through the slot 50 the dirt and dust enters the space 52 (FIG. 5) and thereafter is carried away by suction through the duct 22 in wand 13.

Rigidly coupled with one end of the brush spindle 46 is the toothed pinion gear 56 (driven gear) which when rotated rotates the brush 16. As indicated at FIGS. 2 and 3 an end section of the motors armature shaft is hobbed to form another toothed pinion gear 54 (driving gear). An endless belt 58 having a plurality of teeth 60 60 on the inside surface thereof is meshingly engaged with the toothed driving gear 54 and the toothed driven gear 56. The energization of the motor 12 rotates the driving gear 54 which drives the belt 58. The belt, in turn, rotates the driven gear 56 which causes rotation of the brush 16. The arrows in FIG. 2 indicate the rotational directions of the driving gear 54, the belt 58 and the driven gear 56.

In order to prevent that section of the belt 58 which is meshed with the driving gear 54 from getting out of toothed engagement therewith when the brush 16 and the driven gear 56 become stalled there is provided the arcuate shroud 62 which, as shown in FIGS. 1-4, may be integrally formed with the die-cast end bell 34 of the motor. As shown in FIG. 3 the arcuate shroud 62 is spaced a small distance from the smooth outside surface of the belt 58 and the surface of the shroud situated opposite the smooth belt surface is also smooth. Should the driven gear 56 become stalled and the belt 58 tend to move outwardly out of engagement with the teeth on the driving gear 54, a smooth surface of the shroud 62 will abut against the smooth surface of the belt 58 and prevent disengagement of the belt teeth from the gear 54. As indicated the arcuate shroud 62 lies substantially on the circumference of a circle which is concentric to the circumference of the driving gear 54.

FIG. 6 is an illustration of a prior art belt drive arrangement which does not include an arcuate shroud for ensuring that the belt teeth stay in engagement with the teeth of the driving gear 54 when the brush 16 stalls. In FIG. 6 it is assumed that the driven gear 56 is not rotating because the brush 16 coupled therewith has be.- come stalled. However, the driving gear 54 on the armature of the motor 12 rotates at high speed and the teeth of the driving gear 54 successively slip out of engagement with the belt teeth, the belt, as shown, moving outwardly from the gear 54 so that the few remaining teeth of the gear 54 are but partially meshed with the teeth of the belt 58. Belt 58 does not rotate. Rather, as indicated in the dotted line representation of FIG. 6, the slack side of the belt (upper side) vibrates upwardly and downwardly. By employing an arcuate shroud, such as shroud 62, that portion of the belt which engages the driving gear 54 is forcibly maintained in meshing engagement with the driving gear. As a result, the stalling torque of the brush is transmitted through the belt 58 to the driving gear 54 to overload the motor thereby enabling the circuit breaker 14 to disconnect the motor from the electric circuit, thereby preventing breakage of the belt and damage to the motor. After the obstruction causing the brush to stall has been removed the reset button 64 on the breaker 14 can be pushed to reenergize the motor.

Repeated success in preventing belt breakage and motor damage has been achieved by employing a shroud such as 62 in many surface cleaning suction nozzles which have rotary brushes such as 16. While the following more or less specific ratings and dimensions of the component parts of one such type of cleaning nozzle are set forth for purposes of illustration, it is to be understood that such ratings and dimensions are not limitativ-e of the invention:

The motor 12 which has been used is a universal motor having approximately A HI. output, operating from an input source of 110 volts, 60 cycles, single phase. The armature speed of the motor is between 16,000 and 17,000 r.p.m. when the brush 16 is not rotating against the surface to be cleaned.

The belt 58 is a substantially non-stretchable belt having a pitch circumference of approximately 8.6 inches with 46 teeth on the inside surface thereof. The belt is fashioned from neoprene rubber having a nylon fabric reinforcing the tooth faces and is also laterally reinforced between the body of the belt and the beginning of the toothed structures by synthetic fibres. The driving pinion gear 54 which is formed integral with the armature shaft has an outside diameter of approximately 0.36 inch and has 6 teeth thereon. The driven gear 56 has an outside diameter of approximately 1.1 inches and has 19 teeth on its circumference.

While one specific embodiment of the invention has been shown and described, it is to be understood that this has been done for the purposes of illustration only and that the scope of the invention is not to be limited thereby, but is to be determined from the appended claims.

What we claim is:

1. In a surface cleaning element wherein a surface cleaning brush is coupled for rotation with a driven toothed gear which is rotated by an endless toothed belt which is, in turn, rotated by an electric motor-driven toothed driving gear, first means for preventing the teeth of the endless belt from getting out of engagement with the teeth of the driving gear and preventing relative circumferential disengagement therebetween in the event that the cleaning brush becomes overloaded in order to positively overload the driving gear and its motor, whereby the current input to said motor is increased and second means for turning off the motor in response to the overload current input whereby breakage of the belt and damage to the motor are prevented.

2. The surface cleaning element set forth in claim 1 wherein the endless belt has a smooth outside surface and a series of teeth along its inside surface which meshingly engage with the teeth of the driving gear, and wherein said first means comprises a stationary arcuate member spaced at a small clearance distance from the outside surface of an arcuate length of that section of the belt which is in meshing engagement with the driving gear, said arcuate member being abutted by the belts outside surface as the belt tends to move away from the driving gear due to overloading of the cleaning brush whereby said arcuate member maintains the teeth of the belt in meshing engagement with the teeth of the driving gear.

3. The surface cleaning element set forth in claim 1 wherein said first means is stationary and the belt, when rotating, passes between said first means and an arcuate section of the periphery of the rotating driving gear, said first means serving to prevent the belt from radially moving an appreciable distance outwardly from the driving gears periphery thereby maintaining the teeth of the belt in meshing engagement with the teeth of the driving gear.

4. In combination with an electric motor-driven toothed gear driving a toothed endless belt, a load-carrying gear driven by said belt, means for maintaining the teeth of the belt in meshing engagement with the teeth of the gear and preventing relative circumferential disengagement therebetween in the event that the belt becomes overloaded to positively overload the motor whereby the current input to said motor is increased, and means for electrically deizing the motor in response to the overload current input.

5. In combination: an electric motor; a circuit breaker electrically connected with said motor; a toothed driving gear rotated directly by said motor; a toothed driven gear; a load rotated directly by said driven gear; a toothed endless belt meshed with the teeth of said driving and driven gears, said endless belt being rotated by said driving gear and rotating said driven gear, and means for preventing disengagement of the teeth of said endless belt from the teeth of said driving gear and preventing relative circumferential disengagement therebetween in the event that sai-d driven gear becomes stalled due to said load becoming stalled in order to stall said driving gear and overload said motor whereby the current input to said motor is increased thereby causing said circuit breaker to electrically deenergize said motor in response to the overload current input.

6. In a surface cleaning suction nozzle, a surface-agitating rotary brush, a driven toothed gear directly connected to said brush for rotating said brush, an electric motor, a toothed driving gear directly connected to said motor for rotation thereby, an endless belt having teeth on the inside surface thereof in meshing engagement with said driven and driving gears, said belt having a relatively smooth outside surface, a stationary smooth-surfaced arcuate shroud which lies on the circumference of a circle which is concentric with the circumference of said driving gear, the smooth surface of said shroud being arranged adjacent to but spaced a small distance from the smooth surface of that section of belt on the rotating driving gear which becomes slack, said smooth-surfaced shroud abutting said slack belt sections smooth surface and preventing the teeth in the slack belt section from moving out of meshing engagement with the teeth of the driving gear and preventing relative circumferential disengagement therebetween in the event that the rotary brush becomes overloaded whereby the belt transmits the overload to the driving gear to overload the motor to thereby increase the current input to said motor, and a circuit breaker for electrically deenergizing said motor in response to the overload current input.

References Cited by the Examiner UNITED STATES PATENTS 1,972,695 9/ 1934 Staude 318-474 X 2,461,261 2/ 1949 Drisko 74-472 X 2,596,672 5/1952 Gard et al 318-474 X 2,674,896 4/ 1954 Arones.

2,718,153 9/1955 Dean 74-240 X 2,726,364 12/ 1955 Merritt 318-475 2,766,417 10/ 1956 Merritt 318-475 DAVID J. WILLIAMOWSKY, Primary Examiner.

DON A. WAITE, Examiner.

J. A. WONG, Assistant Examiner. 

1. IN A SURFACE CLEANING ELEMENT WHEREIN A SURFACE CLEANING BRUSH IS COUPLED FOR ROTATION WITH A DRIVEN TOOTHED GEAR WHICH IS ROTATED BY AN ENDLESS TOOTHED BELT WHICH IS, IN TURN, ROTATED BY AN ELECTRIC MOTOR-DRIVEN TOOTHED DRIVING GEAR, FIRST MEANS FOR PREVENTING THE TEETH OF THE ENDLESS BELT FROM GETTING OUT OF ENGAGEMENT WITH THE TEETH OF THE DRIVING GEAR AND PREVENTING RELATIVE CIRCUMFERRENTIAL DISENGAGEMENT THEREBETWEEN IN THE EVENT THAT THE CLEANING BRUSH BECOMES OVERLOAD IN ORDER TO POSITIVELY OVERLOAD THE DRIVING GEAR AND ITS MOTOR, WHEREBY THE CURRENT INPUT TO SAID MOTOR IS INCREASED AND SECOND MEANS FOR TURNING OFF THE MOTOR IN RESPONSE TO THE OVERLOAD CURRENT INPUT WHEREBY BREAKAGE OF THE BELT AND DAMAGE TO THE MOTOR ARE PREVENTED. 